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Exam 3 - Coggle Diagram
Exam 3
Intermediate growth
Trait evolution
Apomorphy
Synapomorphy
Autapomorphy
Plesiomorphy
Homoplasy
apical meristem
mitosis
prophase
metaphase
anaphase
telophase
2D to 3D switch
Linear growth such as filamentous algae
Leafy shoot growth in three dimensions
Bifurcating sporophyte
Splitting shoot tip into 2
Laid foundation for multiple sporangia
Terminal sporophyte replaced
Displace sporangium
Some tips sterile
Necessary prior to indeterminancy
Bifurcate branching
Evolved prior to vascularization
Lycophytes various branching structures
Equal branching
Unequal branching
Indeterminacy
Vascular plant synapomorphy
Grow continuously
Displace terminal sporangia onto lateral branches
convergent evolution
Indeterminate meristems evolved independently
Vascular plant meristems may have evolved independently
Shoot apical meristem
Totipotent region
Continuously divides
Matures in to transition tissues
Vascularization
xylem
.
No specialized cells
Live in perennially wet substrates (stream sides)
More derived homoiohydric
Poikilohydric
Stayed small to reduce demand for water
hydroids
Bryophytes
Water conducting cell
Apomorphic trait (similar function but different origin) to true vascular tissue
No lignin
Tracheary elements
Die at maturity
Thickened lignin walls
Stepwise progression
Partially thickened
Lignified tracheids
during devonian
Increase in xylem content
Increase in tracheid size
Increase in tracheid reinforcement
early tracheids
Water transport only (no support)
lignified
Relatively long and wide
Ferns
Lycophytes
Pit membranes
True tracheids
Lignified with ornamented walls
Evolved likely once
Function in both
Tapered at ends
Pine tracheids
Function in water movement & support
Torus-margo pit membrane
Vessel elements
Large diameter
Dead and maturity
Open, digested end walls
Angiosperms
Tracheid vs Vessel element
Pit membranes are absent in perforations of mature vessel elements
Conductive area greater in end wall of vessel elements compared to lateral walls; tracheids are similar
Perforation plate morphology different than lateral-wall pitting in vessel elements; tracheid endwall similar to lateral
Vessel elements have a greater diameter than tracheids
Vessel elements are shorter than tracheids
Gymnosperm vs Angiosperm
Vessels can have greater
Vessel elements may be short but the vessel can be much longer
yields greater conductivity in vessel elements
Lowers the cost (construction & transpiration)
Having vessels permits more fiber (hardwood vs softwood)
Downside is greater cavitation risk
Vessel element differentiation
Apical meristem
Vacuolization
Elongation
Secondary cell wall
Dead at maturity
Evolutionary perspective
Tracheophytes
Synapomorphy
All have vascular tissue
Cell type varies
Vascular architecture diverse
Early evidence
Tracheids
Annular thickenings
Cooksonia
Thought to be true tracheids
Lycophytes
Early vascular group
Created towering forests during Carboniferous
Phloem
Food conducting cells
Specialized plasmodesmata in end walls
Alignment along longitudinal arrays of endoplasmic microtubules*
Breakdown of tonoplast
Rarely some species have nuclear breakdown
Features common to sieve cells
Widespread in bryophytes
Sieve cells & albuminous cells
ac aka Strasburger cells
Gymnosperms only these
Earlier lineages with various types including transitional = sieve elements
Sieve area pores narrow
Uniform sieve areas
Transport of
Photosynthate
Hormones
Electric signals
Sieve tube element features
Many sieve tube elements together = sieve tube
Primary cell wall
Living protoplasts at maturity
Sieve plate
Callose & callose plugs
Sieve tube element & companion cell features
Transport of
Photosynthate
Hormones
Electric signals
Sieve tube element
Sieve plate
Sieve pore
Lateral sieve area
P protein
Plastid
Smooth ER
Mitochondria
Companion cell
Branched plasmodesmata
Vacuole
Nucleus
mitochondria
Plasmodesmata connections
Sieve tube & companion cell from same mother cell
Connected by a large quantity of plasmodesmata
One pore in sieve tube area branched into many on companion cell side
Sieve tube contents
P-proteins
Forisomes
Sieve element plastids
Mitochondria
Endoplasmic reticulum
Phloem differentiation
Cell wall thickened
Cytoplasmic clearing
Callose deposited around terminal plasmodesmata
Nuclear break down
Formation of sieve plate & pores
Vascular primary tissue arrangement in shoots
Arrangement changes within a plant
Root and shoot have different arrangements
Key features to Monocots and Eudicots
Monocot
Eudicot
Increasing complexity
Complexity increased
Stem diameter increased
Plant height increased
Led to compartmentalization
Selected for a woody habit
3 major stele types
Protostele (~420Ma)
Earliest
Solid vascular strand
Phloem surrounds xylem or interspersed
Siphonostele (~407Ma)
Ring of phloem, xylem, surrounding pith
Eustele (~390Ma)
Most complex
Strands of phloem & xylem separated by parenchyma
progymnosperms
archs
Based on xylem maturation
Protoxylem
Metaxylem
Exarch
Protoxylem outside metaxylem
Endarch
Protoxylem in middle
Mesarch
Protoxylem surrounded by metaxylem
Lycophyte
Protostele
Most ancestral type of stem vasculature
Exarch
Ferns
Siphonostele
Xylem surrounded by phloem
Endarch
Monocotyledonae
Atactostele
Numerous vascular bundles scattered throughout stem
No pith
Vascular bundles often surrounded by sclerenchyma
Eudicotyledonae
Eustele
Phloem outside xylem
Bundles separated by parenchyma
Endarch
Metaxylem outside protoxylem
Vascular bundle supported by sclerenchyma, bundle cap
Wood
Environmental change
Amount of water loss per carbon gained increased after Silurian
Carboniferous period greatly drained atmospheric CO2
Water demand is relatively high
Selection pressure for wood
Increased competition for light selected for
Higher rates of transpiration
Likely evolved 5 times
Loss of secondary growth
Monocotyledonae
Arborescent
First tree
Lepidondrids
Carboniferous
~320mya
Vascular cambium only divided internally
Archaeopteris
Devonian/Carboniferous
Reproduced via spores
Extant lineages
Lycophytes
Euphyllophyte
Secondary growth
Complex plant development
Growth in girth
Produce secondary
xylem (wood)
phloem (inner bark)
Ground tissue (rays)
Continuous circular ring growth
Vascular cambium
Fusiform initials
Ray initials
Periclinal division
Anticlinal division
Divisions 3D
Wood block
Unique for each face
Longitudinal
Transverse
Radial
Initials
Fusiform - longitudinal
Ray - radial
Annular rings
Xylem secondary cell walls robust
Phloem is crushed
Ring width determined by season and environment
Alternation of
Early wood
Late wood
Early vs Late
Based on season or environment
Spring to fall
Larger elements to smaller elements
Sapwood vs heartwood
Sapwood
Functions in water transport
Heartwood
Functions in storage
Can no longer transport water
Softwood vs Hardwood
Softwood
Tracheids only
Little room for fibers
Gymnosperms
Hardwood
Vessel elements’ efficiency permit space for fibers
Angiosperms
Eudicot cross section
Plant armor
Periderm
Phellem
Cork
Phellogen
Cork cambium
Outer bark
Inner bark
Phloem & cortex
Roots
Origins
Rhizoid
Uni-multicellular projections
Anchorage
Some with mineral uptake
Genes
Rhizomorphs
Lepidodendrales extinct
Dichotomous rooting system
Lateral stigmarian rootlets
Similar to roots
No root cap
Extant species lycophyte
Shoot turned root
Rhynie chert, Zosterophyllophyta, Early Devonian
Upright stem, prostrate stems, downward (rootlike) stems
Root transition
Early without root hairs
Intact epidermis covered root tip
Devonian lycophyte Asteroxylon mackiei
Independent evolution of
endodermis
root cap
Root meristem
Diversity of arrangement used to infer phylogeny
Similar genes across plant taxa
Similar genes in shoot to root
Root body plan
Root types
primary root
Derived from radicle
Main root
Mainly dominant in eudicots
Mainly ephemeral in monocots
lateral roots
Adventitious roots
seminal roots
General root plan
Highly differentiated multicellular axis
Found only in sporophytes of vascular plants
functions
Anchors plant body to substrate
Absorbs water
Absorbs dissolved minerals
common features
Apical meristem & root cap
Pericycle
Endodermis
Root hairs
Cortex
apical meristem
Quiescent center
Behind root cap
root cap
Protect underlying tissues
Cells that slough off
Secrete mucilage
Evolved independently
lycophyte
Euphyllophyte
pericycle
Pluripotent
Initiation of lateral root development
Just inside the endodermis
root hairs
Single celled
Major absorption of water and minerals
Via osmosis from hypotonic soil solution to hypertonic cells
Delicate
Short-lived
Cortex
Large storage area
Bound by endodermis and epidermis
endodermis
Casparian strip
Prevents apoplastic movement of water
Forces water to move through cell membranes to be filtered
Organizational diversity
lycophytes
Selaginella sp example
No root cap
No root hairs
monocot
Diversity
Pith in center
Endodermis
Surrounded by cortex
monocot details
Epidermis
Cortex
Endodermis
Pericycle
Xylem
Phloem
Pith
eudicot
Diversity
No pith
Endodermis
Cortex
eudicot details
Epidermis
Cortex
Endodermis
Pericycle
Xylem
Phloem
Leaves
Phyllad tissues
Collenchyma
Ground tissue
Thickened primary cell walls
Main function in flexible support
Found in bundle sheath of veins in some species
Aerenchyma
Large air pockets for buoyancy in aquatic plants
Main function permit gas-exchange
Contains air spaces from cells being digested
Specialized parenchyma
Ground tissue
Chlorenchyma
Main function is photosynthesis
Contains chloroplasts
Specialized parenchyma
Ground tissue
vascular tissue
phloem
in veins
xylem
epidermis
Main function in protecting the internal tissues
Often cutenized
Guard cells
Epidermal cells
Dermal tissue
Phyllad evolution
Zimmerman telome theory
By Devonian euphylls widespread
webbing
planation
Overtopping
Evolution of euphylls
enation theory
Fossils consistent
Vascular strands entered later
Progressive elaboration of epidermal outgrowths
Lycophyte leaves
Varied leaf development
Euphylls
From flanks of multicellular shoot apical meristem
Pool of recruited cells
Seed plants
frond
Shoot like development
Mitosis of single apical cell
Monilophyte
Microphyll
mitosis of two epidermal cells
lycophyte
Mitosis of a single cell
moss
liverwort
initial constraints
High atmospheric global temperatures
Low stomatal densities
Low capacities for water uptake prior to root evolution
Lacking efficient vascular transport in leaves
Polyphyletic origin
Earliest evidence of true leaves
Lycophytes
Euphyllophytes
Optimal light interception
Indeterminate growth proceeded leaf development
Leaves initiated in regular patterns around stem
Optimize light interception for photosynthesis
Convergent evolution
Leaves had at least 5 independent origins
Spermatophyte sporophyte
Monilophyte sporophyte
Lycophyte sporophyte
Moss gametophyte
Liverwort gametophyte
Phyllad organization
lycophylls
Microphyll
Single vascular trace along center of blade
Vascular strand connects directly to stem
Mesophyll
Epidermis
Stomata
Monocot leaf
epidermis
Adaxial (outer) & abaxial (towards stem)
Covered by cuticle
Contains stomata
bulliform cells
mesophyll
veins
Surrounded by bundle sheaths
eudicot leaf
epidermis
Dermal tissue
Cuticle
Upper & lower
Mesophyll
palisade
spongy
veins
Xylem on top phloem on bottom
Bundle sheath cells
